Function Parameters - need help !!!

Hi all,

I am a new joinee to this mailing list. I am using PostgreSql for my
project. We are trying to port a few stored procedures written in SQL to
PGSQL. But i am finding difficulties in doing that. I m new to
Postgresql....dont know much about it. I tried a lot of books and online
documents.....no go. I have problems in passing default values to function
paraameters. I would really appreciate if anyone can help me out with this.
The function I am trying to port is as follows : 

CREATE PROC PP_ReadPointByValue
@SessionID int = NULL, --these r default parameters
@SPSID int = 1,--default value
@ParameterName nvarchar (50) = NULL, -- if NULL read all parameters
@NumValue  real = NULL,
@StrValue nvarchar (255) = NULL,
@ParameterID int = NULL

Now how do I specify default parameters to the arguments in Plpgsql .

> With Best Regards 
> Pradeep Kumar P J 
> Honeywell_______________________________________
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